1. Field of the Invention
The present invention relates generally to the field of molecular pathology and biomedical devices. More specifically, the present invention relates to a cryoarray device/system for creating frozen tissue arrays for subsequent assaying.
2. Description of the Related Art
The implementation of high-throughput genetic technologies, such as oligonucleotide microarrays, generates myriad points of data. The identified potential candidate genes need to be further characterized and selected using a large number of well-characterized tumors and stringent criteria. Tissue microarrays allow for such high-throughput expression profiling of tumor samples, additionally providing information at the microanatomical level.
Sections cut from tissue arrays allow parallel detection of DNA, e.g., by fluorescence in-situ hybridization (FISH), RNA, e.g., by mRNA in-situ hybridization (mRNA ISH) or protein, e.g., by immunohistochemistry (IHC) targets in each of the multiple specimens in the array. Each microarray block can be sectioned up to 200-300 times. Therefore, tens of thousands of tissue microarray sections can be obtained from a set of tissue specimens in one recipient block. This substantially facilitates molecular profiling of very large numbers of cancer tissues and allows the generation of large-scale correlative databases including clinical information and molecular data (including images), while ensuring that the donor blocks from which the tissue cores are removed can continue to be utilized so that research materials are not destroyed.
In early 1998, Kononen et al. (1) described a tissue microarray xe2x80x9cchipxe2x80x9d that had been developed for high-throughput molecular profiling of tumor specimens. Tissue microarrays enable rapid in-situ analysis of up to 1000 tumors or other tissues in a single experiment. In the method of Kononen, original tissue sample sources are morphologically representative regions of regular formalin-fixed paraffin-embedded tumor blocks. Core tissue biopsies are taken from individual xe2x80x9cdonorxe2x80x9d paraffin-embedded tumor blocks and precisely arrayed into a new xe2x80x9crecipientxe2x80x9d paraffin block using a custom built instrument. Thereafter, Bubendorf et al. published data of a survey of gene amplifications during prostate cancer progression by high-throughput fluorescence in-situ hybridization on tissue microarrays (2). The first hand-held paraffin tissue array apparatus was later marketed.
Tissue microarrays consisting of 0.6 mm biopsies of paraffin-embedded tissues have been used for various clinicopathological studies. This size is sufficient for assessing morphological features of the analyzed tissues on many samples. However, the size of the biopsy used in these arrays may not be representative of the whole tumor specimen because of tissue heterogeneity. Additionally, paraffin tissue arrays have distinct limitations in maintaining intact RNA transcription levels, as well as proteins and other molecules (i.e., lipids) due to the fixatives and chemical reagents required for the paraffin process. Thus, tissue microarray technology using paraffin-embedded tissues can reach its limits for the detection of RNA targets or certain proteins. The use of a cryoarray strategy would overcome these limitations and would allow for the processing of multiple frozen tissue specimens and/or cell lines on a single tissue block.
Therefore, it would be beneficial to have an effective means and a system for creating tissue arrays that allow all molecules to be assayed at the expression level and simultaneously visualized at micro-anatomical levels. Specifically, the prior art is deficient in the lack of an effective means/system for creating a cryoarrays for frozen tissue assays. The present invention fulfills this long-standing need and desire in the art.
In one embodiment of the present invention, there is provided a cryoarray device comprising a mold plate having an upper and a lower surface; mold alignment pins where the mold alignment pins are perpendicularly attached to the lower surface of the mold plate; an ejector plate having an upper surface and a lower surface where the plate has holes between the upper surface and the lower surface; ejector pins having ejector thumb pads attached to an upper surface of the ejectors pins and connecting the mold plate and the ejector plate; and cryoarray pins, of equal number to the holes in the ejector plate and aligned with the holes in the ejector plate.
In another embodiment of the present invention, there is provided a cryoarray system for forming an array for frozen tissue, comprising a tissue mold; an embedding medium filling the tissue mold, frozen within the tissue mold where the frozen embedding medium forms a recipient tissue block; and the cryoarray device which is placed in the tissue mold containing the embedding medium, but prior to freezing the embedding medium; where freezing the embedding medium around the cryoarray pins of the device creates grid holes into the recipient block when the cryoarray device is separated from the recipient block so that an array is formed in the recipient block for frozen tissue.
In yet another embodiment of the present invention, there is provided a method for preparing tissue for assays, comprising the steps of selecting at least one frozen tissue core from a donor block; inserting each of the frozen cores into a grid hole of the recipient block of the cryoarray system disclosed supra thereby forming a frozen tissue array; cutting sections from the array; and assaying the sections.
Other and further aspects, features, and advantages of the present invention will be apparent from the following description of the presently preferred embodiments of the invention given for the purpose of disclosure.